Application information: monitoring and protection

L6924U

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Doc ID 14716 Rev 2

Based on Equation 14 and Equation 17, it derives that:

Equation 18

The temperature hysteresis can be estimated by the equation:

Equation 19

the characteristics of the NTC manufacturers (e.g. the 2322615 series by VISHAY). At low

temperature, the hysteresis is approximately:

Equation 20

Obviously at high temperature hysteresis is:

Equation 21

Equation 22

And:

Equation 23

If a PTC connected to GND is used, the selection is the same as above, the only difference

is when the battery temperature increases, the voltage on the TH pin increases, and vice

versa. For applications that do not need a monitor of the battery temperature, the NTC can

In this case, the voltage at the TH pin is always inside the voltage window, and the charge is

always enabled.

7

50

0

=

°

°

C

NTC

C

NTC

R

R

T

TH

HYS

TH

TH

HYS

NTC

V

V

V

T

×

−

=

_

C

NTC

mV

mV

mV

T

C

HYS

°

×

−

=

°

0

900

780

900

0

C

NTC

mV

mV

mV

T

C

HYS

°

×

−

=

°

50

225

248

225

50

C

mV

mV

mV

T

C

HYS

o

5

.

2

051

.

0

900

780

900

0

≅

×

−

=

°

C

mV

mV

mV

T

C

HYS

o

5

.

2

039

.

0

225

248

225

50

−

≅

×

−

=

°